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https://www.blablacar.fr

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
75
GRADE
C
FIX
4
REVIEW
2
PASS
6
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
74
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

640 ms

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

1.11 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

162 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.334

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

1.83 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

2.88 s

Page Load Progression

375 ms
750 ms
1.1 s
1.5 s
1.9 s
2.2 s
2.6 s
3.0 s
Checks
14
6 PASS 2 REVIEW 4 FIX
D
Page Weight Budget
Action
2.5 MB transferred, 93 requests
FIX
2.5 MB transferred, 93 requests
Warning::
Page weighs 9.6 MB (2.5 MB transferred)
Warning::
JavaScript is 1.6 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.6 MB
Info::
Fonts are 208 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 208 KB
Info::
93 HTTP requests
Info::
Estimated 0.53 g CO2 per page load
2.5 MB / 2.4 MB budget
2.5 MB transferred
93 requests
0.53 g CO2 per page load
JavaScript 1.6 MiB 64%
Images 423.1 KiB 16%
HTML 232.9 KiB 9%
Fonts 208.2 KiB 8%
CSS 48.8 KiB 2%
Other 6.6 KiB 0%
Other 3.6 KiB 0%
Other 1.2 KiB 0%
Other 681 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (2.5 MiB of 2.5 MiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
F
JS Bundles
Action
32 scripts, 658 KB unused
FIX
32 scripts, 658 KB unused
Warning::
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b...: 249 KB unused (61%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.blablacar.com/k/a/index.59085c37e31fdd...: 218 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-TVP...: 79 KB unused (45%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.blablacar.com/k/a/6187.cab3118d515f4ea...: 48 KB unused (73%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sdk.privacy-center.org/sdk/c8e2e67c354c0d6...: 43 KB unused (48%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 658 KB
658 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b7.js410 KB249 KB (61%)✓3rd
https://cdn.blablacar.com/k/a/index.59085c37e31fdd97.js436 KB218 KB (50%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TVPFSZ175 KB79 KB (45%)✓3rd
https://cdn.blablacar.com/k/a/6187.cab3118d515f4ea4.chunk.js66 KB48 KB (73%)✓3rd
https://sdk.privacy-center.org/sdk/c8e2e67c354c0d6dec2981e079061b37f6a1f337/modern/sdk.c8e2e67c354c0d6dec2981e079061b37f6a1f337.js90 KB43 KB (48%)✓3rd
https://try.abtasty.com/8c952bdd9cb88033ffef07632e185107/main.51be40c215b8bdf2eeec.js46 KB20 KB (44%)✓3rd
https://ddome-tag.blablacar.com/tags.js43 KB—✓3rd
https://cdn.blablacar.com/k/a/5168.871296c462df99ba.chunk.js2 KB—✓3rd
https://cdn.blablacar.com/k/a/7663.0735c7dfe8c4449e.chunk.js3 KB—✓3rd
https://cdn.blablacar.com/k/a/1237.5d60fe73894ef6ad.chunk.js2 KB—✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: max-age=0, private, no-cache, no-store, must-revalidate
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=0, private, no-cache, no-store, must-revalidate

DirectiveValueMeaning
max-age0Cache for 0 seconds
private—Only browser cache, not CDN/proxy
no-cache—Cache but always revalidate first
no-store—Never cache this response
must-revalidate—Must recheck with server after expiry
C
Image Optimization
Action
17 images, 0 KB saveable
REVIEW
17 images, 0 KB saveable
Warning::
https://cdn.blablacar.com/k/a/images/train-ddad238... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.blablacar.com/didomi/blablacar-logo-2.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
17 images 423 KB
0 oversized -0 KB
6 legacy format
2 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

C
JS Execution Cost
Action
1315ms total JS execution
REVIEW
1315ms total JS execution
Warning::
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b...: 397ms CPU time
Info::
https://cdn.blablacar.com/k/a/index.59085c37e31fdd...: 243ms CPU time
Info::
Unattributable: 198ms CPU time
Info::
https://www.blablacar.fr/: 196ms CPU time
Info::
https://ddome-tag.blablacar.com/tags.js: 90ms CPU time
Warning::
Third-party scripts: 1119ms (85% of total)

Main Thread Breakdown

Script Evaluation 56% Other 20% Script Parsing & Compilation 12% Style & Layout 5% Garbage Collection 3%
ScriptTotalScriptingParse/CompileParty
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b7.js397ms289ms40ms3rd
https://cdn.blablacar.com/k/a/index.59085c37e31fdd97.js243ms167ms71ms3rd
Unattributable198ms27ms0ms3rd
https://www.blablacar.fr/196ms10ms2ms1st
https://ddome-tag.blablacar.com/tags.js90ms78ms5ms3rd
https://sdk.privacy-center.org/sdk/c8e2e67c354c0d6dec2981e079061b37f6a1f337/modern/ui-web-en-web.c8e2e67c354c0d6dec2981e079061b37f6a1f337.js69ms47ms5ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TVPFSZ64ms49ms14ms3rd
https://cdn.blablacar.com/k/a/9245.708db02cfe26ed36.chunk.js58ms38ms2ms3rd
A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
5 fonts (208 KB)
PASS
5 fonts (208 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

5

208 KB total

Render-blocking

0

of 5

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 640 ms LCP 1.1 shttps://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Medium-1.woff2GT-Eesti-Pro-Display-Me... https://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Medium-1.woff2 — 59.2 KiB — 0 ms — font-display: swaphttps://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Regular-1.woff2GT-Eesti-Pro-Display-Re... https://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Regular-1.woff2 — 56.4 KiB — 0 ms — font-display: swaphttps://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-UBold.woff2GT-Eesti-Pro-Display-UB... https://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-UBold.woff2 — 59.0 KiB — 0 ms — font-display: swaphttps://static.captcha-delivery.com/common/fonts/open-sans/open-sans.woff2open-sans.woff2 https://static.captcha-delivery.com/common/fonts/open-sans/open-sans.woff2 — 16.8 KiB — 0 ms — font-display: swaphttps://static.captcha-delivery.com/common/fonts/open-sans/open-sans-300.woff2open-sans-300.woff2 https://static.captcha-delivery.com/common/fonts/open-sans/open-sans-300.woff2 — 16.8 KiB — 0 ms — font-display: swap
GT-Eesti-Pro-Display-Me... woff2 swap
Size 59 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
GT-Eesti-Pro-Display-Re... woff2 swap
Size 56 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
GT-Eesti-Pro-Display-UB... woff2 swap
Size 59 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
open-sans.woff2 woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
open-sans-300.woff2 woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Optimization checklist
  • Preload critical fonts (priority=high)
  • Use woff2 format for all fonts
  • Set font-display to swap, optional, or fallback
  • Subset large fonts (≤100 KB each)
A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Google Cloud

Network Waterfall
93 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
85% of JavaScript execution is third-party
First-party Third-party 1119ms · 1146KB · €12/mo
cdn.blablacar.com
Other
Costly
Execution 397ms
Transfer 410 KB
Unused 61%
Monthly Cost €4/mo
cdn.blablacar.com
Other
Costly
Execution 243ms
Transfer 436 KB
Unused 50%
Monthly Cost €3/mo
Unattributable
Other
Optional
Execution 198ms
Transfer 0 KB
Monthly Cost €2/mo
ddome-tag.blablacar.com
Other
Optional
Execution 90ms
Transfer 43 KB
Monthly Cost €1/mo
sdk.privacy-center.org
Other
Optional
Execution 69ms
Transfer 52 KB
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 64ms
Transfer 175 KB
Unused 45%
Monthly Cost €1/mo
cdn.blablacar.com
Other
Optional
Execution 58ms
Transfer 31 KB
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • cdn.blablacar.com adds 397ms and costs ~€4/month
  • cdn.blablacar.com adds 243ms and costs ~€3/month

85% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.

Learn more ▾

Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.

Source: web.dev

cdn.blablacar.com takes 397ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

61% of cdn.blablacar.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

cdn.blablacar.com takes 243ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

50% of cdn.blablacar.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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